1. Technical Field
This application relates to a closure device and more particularly to a device for closing septal defects such as the patent foramen ovale.
2. Background of Related Art
Septal defects are perforations in the septum, a wall dividing two cavities, such as the atria of the heart. A trial defects can occur congenitally (by birth) or develop later such as after a heart attack.
One type of atrial defect is the foramen ovale. The foramen ovale is a valve-like opening between the two atria of the heart in the fetus. In most cases, it closes shortly before or after birth as fibrous tissue growth seals the opening. However, in some cases, the opening (defect) remains open (patent), allowing blood to shunt across the defect from the left atrium to the right atrium. This means that the un-oxygenated blood flows directly from the right side to the left side of the heart, where it travels through the aorta to the brain and other parts of the body. This can lead to life-threatening strokes as clots can travel to the brain. Additionally, since blood shunts from the higher pressure left ventricle into the lower pressure right side heart chambers and pulmonary arteries, this increase in flow at the high pressure can cause cardiac failure and even death.
One approach to treatment to prevent travel of the life-threatening blood clots is the administration of medications to break up the blood clots. However, these blood thinning medications are expensive, increase the risk of bleeding and could have adverse side effects. Another approach is to perform invasive open heart surgery to close off the patent foramen ovale (PFO) by suturing the tissue to close the opening or by suturing a patch to cover the defect. Such invasive open heart surgery is time consuming, traumatic to the patient, increases patient risk and recovery time, and increases costs as extended hospital stays are required.
It is therefore recognized that a minimally invasive approach to closing the septal defect to prevent the aforementioned migration of blood clots into cranial circulation and prevent cardiac overwork by high pressure flow would be beneficial. These devices, however, need to meet several criteria.
Such minimally invasive devices need to be collapsible to a small enough dimension to enable delivery through a small incision while being expandable to a sufficiently large dimension with sufficient stability to ensure sealing of the septal defect. The smaller the profile when collapsed the better the access and insertion. Providing a low profile once positioned is also advantageous because it minimizes disruption of blood flow.
There have been several attempts in the prior art to provide minimally invasive devices for closing a PFO. For example, in U.S. Pat. No. 5,846,261, a tubular wire braid of shape memory metal fabric is placed in the opening. In U.S. Pat. No. 5,944,738, two discs of braided shape memory wires are utilized. In U.S. Pat. No. 5,425,744, two Dacron covered shape memory frameworks are connected by a wire. In U.S. Pat. No. 5,861,003, two sacs of porous material supported by a wire frame are placed on opposing sides of the opening. In U.S. Pat. No. 6,712,836, a shape memory frame with fingers on both sides of the aperture to hold the plugging structure made of cloth or Dacron which extends through the aperture is disclosed.
It would be advantageous however to provide a device which provides stability to maintain the device position. It would also be advantageous to provide a device which presents a lower implantation profile as well as a lower insertion profile. This would minimize the insertion profile, facilitate passage to and through the defect, and provide less interference with blood flow.
Commonly assigned U.S. patent Ser. No. 10/847,141, filed May 17, 2004, discloses a device for closing vessel apertures. The present application provides a closure device with a reduced profile internally supported patch adapted for closing septal defects such as the patent foramen ovale.